Japanese newspaper advertisements for dietary supplements before and after COVID-19: a content analysis

OBJECTIVES: Public health institutions have alerted consumers about advertising for dietary supplements with false claims of preventing or treating COVID-19. We quantitatively and qualitatively examined newspaper advertisements for dietary supplements before and after the COVID-19 spread. DESIGN: Content analysis. PARTICIPANTS: We analysed advertisements for dietary supplements in two major Japanese newspapers in February–July 2019 and February–July 2020. Our analysis covered 2167 advertisements. RESULTS: The number of advertisements for dietary supplements that claimed to be effective in infection prevention (p=0.009) and improving joint (p=0.002) and digestive functions (p=0.002) significantly increased after the spread of COVID-19 compared with before. Dietary supplements that claimed to be effective in preventing infection were advertised in combination with recommendations for gargling and handwashing. Such terms as ‘defence’ and ‘prevent’ were used to promote the preventive effect. CONCLUSIONS: False and misleading claims in advertising for dietary supplements may result in consumer harm, such as overdosing and failure to take preventive behaviour. While the pandemic continues, there will be an increasing need for disseminating accessible information about the appropriate use of dietary supplements, consumer education and warnings to manufacturers.